1. Field of the Invention
The present invention pertains to novel high nitrogen content, low carbon content energetic compounds. More particularly, the present invention pertains to triazolyl-tetrazinyl-aminotriazine compounds, and complexes and salts thereof. The triazolyl-tetrazinyl-aminotriazine compounds, and their complexes and salts, of the present invention are particularly useful as energetic ingredients for use in pyrotechnics, most particularly smokeless pyrotechnics. The low-smoke pyrotechnic compositions of the present invention may include metal salts together with or added separately into the pyrotechnic composition.
2. Brief Description of the Related Art
Specialized events and amusement parks often exhibit fireworks. These fireworks result from pyrotechnic compositions generally employing a large variety of colorants. However, the smoke resulting from large quantities of burning pyrotechnics may become a nuisance for any spectators in the area, such as obstructing the view to the fireworks or irritating the eyes and throats of the people in the audience.
Fireworks generally employ an initial burst and a main burst mechanism. The main burst includes color-producing pellets, or xe2x80x9cstarsxe2x80x9d, which ignite during the main burst detonation to provide the light and color of a fireworks display. Firework composition have been described in such patents as U.S. Pat. No. 6,312,537 to Hiskey et al., entitled xe2x80x9cLow-Smoke Pyrotechnic Compositionsxe2x80x9d which in part identifies a low-smoke pyrotechnic composition of dihydrazino-s-tetrazine, its derivatives and salts with an oxidizing agent and colorant. Hiskey et al. describes known colorants in pyrotechnics to include cupric oxide, barium nitrate, strontium nitrate and the like, as well as those described in U.S. Pat. No. 5,682,014 to Highsmith et al. The disclosures of these two patents are herein incorporated by reference.
It is an object of the present invention to provide novel triazolyl-tetrazinyl-aminotriazine compounds, and the complexes and salts thereof in pyrotechnic compositions, particularly low-smoke compositions used in fireworks.
The present invention includes a pyrotechnic composition comprising a compound having the chemical structure: 
wherein Z+ comprises H+ or a cation; R comprises a complexing component; and m=1, 2 or 3; n=0, 1, 2 or 3; x=0, 1, 2 or 3; and t=0 or 1. The structure provides the complex and forms of triazolyl-tetrazinyl-aminotriazine.
The present invention also includes a method of making a pyrotechnic composition comprising a triazolyl-tetrazinyl-aminotriazine compound comprising the steps of providing a triazolyl-triaminotriazine precursor and diazotizing the precursor to form the triazolyl-tetrazinyl-aminotriazine, or derivative thereof.
The present invention further includes a pyrotechnic composition comprising a triazolyl-tetrazinyl-aminotriazine compound.
The present invention includes novel triazolyl-tetrazinyl-aminotriazine compounds, and the complexes and salts thereof, that are particularly useful in pyrotechnic compositions with special applicability in fireworks compositions. The fireworks compositions of the present invention are characterized as low-smoke compositions and can be formulated to be essentially smoke-free. Low smoke compositions have decreasing amounts of residual smoke after pyrotechnic bum that are operationally and commercially useful. The triazolyl-tetrazinyl-aminotriazine compounds, and their complexes and salts, provide a high-nitrogen content, low-carbon content energetic material as a principal component within the pyrotechnic composition.
The present invention includes a pyrotechnic composition comprising a compound having the chemical structure: 
wherein Z+ comprises H+ or a cation; R comprises a complexing component; and m=1, 2 or 3; n=0, 1, 2 or 3; x=0, 1, 2 or 3; and t=0 or 1.
The complex form of the triazolyl-tetrazinyl-aminotriazine occurs when Z+ comprises H+, and the value of x is not 0. The complex form include the hydrogen attached to a nitrogen atom in the tetrazinyl ring (see e.g. Example 19B). Complexes of the present invention include, for example, R=Dihydrazino-s-tetrazine, Trihydrazino-s-triazine, 5-Aminotetrazole, N-aminotriazoles, and bis-(1(2)H-tetrazol-5-yl)-amine.
The pyrotechnic compositions herein include metal and non-metal triazolyl-tetrazinyl-aminotriazine compound salts. In one particular embodiment, preferably m=n.
In addition to a complex or salt structure of the triazolyl-tetrazinyl-aminotriazine compound, a useful structure of the triazolyl-tetrazinyl-aminotriazine compound in pyrotechnic compositions includes Z+ being H+, t=1, m=1, n=1, and x=0. When Z+ comprises H+, and m and n are both equal to 1, the calculated heat of formation is approximately 255 kcal/mole (gas phase), and a density of approximately 1.77 g/cc (calcd) which provides significant energy to the pyrotechnic composition.
The Z+ component of the triazolyl-tetrazinyl-aminotriazine compound preferably comprises a cation. As a salt, the compound may be selected from a large number and/or variety of cations as suitable for any particular pyrotechnic. Suitable cations of the present invention include those appropriate to provide color displays from combusting fireworks, particularly metals or amine salts. Metals of the present invention may include, without limitation sodium (Na), cobalt (Co), copper (Cu), aluminum (Al), nickel (Ni), barium (Ba), strontium (Sr), calcium (Ca), potassium (K), iron (Fe), titanium (Ti), magnesium (Mg), antimony (Sb) and the like. Additionally, typical amine salts may include compounds with Z+ being, without limitation, H2NC(NH2)NHCONH2, C(NHNH2)3, NH2NH3, NH4, H2NNHC(NH2)NH2, (H2NNH)2C(NH2), C(NH2)3, (HONH3), and bis(1(2)H-tetrazol-5-yl)-amine (C2H4 N9), the monohydrate of bis(1(2)H-tetrazol-5-yl)-amine (C2H4N9.H2 O). Ignition or combustion of Z+ of the present invention preferably results in a color, however, additional salts and other compositions maybe added in combination with the triazolyl-tetrazinyl-aminotriazine compounds to form the pyrotechnic compositions, as later described. Use of the metal salts of the triazolyl-tetrazinyl-aminotriazine compounds as colorants within the pyrotechnic compositions may generally include the metals conventionally used in pyrotechnic compositions. For example, strontium, barium, copper, and iron salts of triazolo-tetrazino-aminotriazine compounds, and salts thereof, can be expected to yield red, blue, green, yellow, purple, red-purple, and blue-green colorants.
The following structures exemplify non-limiting examples of possible salts for use in the pyrotechnic compositions of the present invention: 
The pyrotechnic composition generally includes the addition of an oxidant to fully consume the carbon and hydrogen components of the pyrotechnic compositions during burning. Suitable oxidizers can generally include, without limitation, one or more alkaline earth metal nitrates, alkaline earth metal nitrites, alkali metal nitrates, alkali metal nitrites, transition metal oxides, such as ammonium perchlorate, alkali perchlorates such as potassium perchlorate and the like, ammonium nitrate, and alkali nitrates such as potassium nitrate and the like, or combinations thereof. Examples of the oxidizer include at least one of an alkali metal or an alkaline earth metal nitrate, a complex salt nitrate, such as Ce(NH4)2 (NO3)6 or ZrO(NO3)2, a dried, hydrated nitrate, such as Ca(NO3)2.4H2O or Cu(NO3)2.2.5 H2O, silver nitrate, an alkali or alkaline earth chlorate or perchlorate, ammonium perchlorate, a nitrite of sodium, potassium, or silver. Additionally, organic compositions such as a solid organic nitrate, nitrite, or amine, such as guanidine nitrate, nitroguanidine and 5-aminotetrazole maybe included. The oxidizer may include silver nitrate or a co-melt or mixture comprising silver nitrate and at least one of an alkali metal nitrate, an alkaline earth metal nitrate, a complex salt nitrate, a dried, hydrated nitrate, an alkali metal chlorate, an alkali metal perchlorate, an alkaline earth metal chlorate, an alkaline earth metal perchlorate, ammonium perchlorate, sodium nitrite, potassium nitrite, silver nitrite, or a complex salt nitrite; and independently a solid organic nitrate, a solid organic nitrite, or a solid organic amine. Alkali chlorates are generally not preferred as oxidizer due to sensitivity concerns. Ammonium perchlorate and ammonium nitrate are preferred oxidizers as the absence of any metal ions is better for control of the fireworks color and eliminates any ash residue. Ammonium perchlorate is particularly preferred as the oxidizer to provide a source of chlorine ions to the pyrotechnic composition. Chlorine ion may be supplied by addition of a metal chloride salt as the colorant or by use of ammonium perchlorate as the oxidizer, or a part thereof. Ammonium nitrate is hygroscopic and compositions including ammonium nitrate must be protected from moisture. The oxidizer is generally added with the triazolyl-tetrazinyl-aminotriazine compounds, or their complexes or salts, in amounts sufficient to provide about three equivalents of free oxygen. For example, the ammonium perchlorate oxidizes the triazolyl-tetrazinyl-aminotriazine anion to carbon dioxide and water if in a ratio of two parts by weight ammonium perchlorate to one part of the organic anion. The same degree of oxidation requires four parts ammonium nitrate. Generally, the compositions can include from about 30 percent by weight to about 60 percent by weight of the high-nitrogen content, low-carbon content energetic material, more preferably from about 35 percent by weight to about 55 percent by weight, together with about 40 to about 60 percent by weight of the selected oxidizer.
As previously described, the pyrotechnic may further include a colorant in addition to the triazolyl-tetrazinyl-aminotriazine complex or salt. Colorants may be additional metal salts, or other compositions, as known in the art. For example, each metal salt has an anticipated colorant effect within a pyrotechnic composition, as each metal has well-known spectra associated with the burning of that metal. These include strontium salts such as strontium nitrate (Sr(NO3)2) or strontium carbonate (SrCO3) for the color red, calcium salts such as calcium carbonate for the color red-orange, barium salts such as barium nitrate (Ba(NO3)2), barium chlorate (Ba(ClO3)2) or boron compounds for the color green, sodium salts such as sodium nitrate for the color orange-yellow, or sodium oxalate (Na2C2O4) or cryolite (3NaF.AlF3) for yellow, copper salts such as copper oxide, CuCO3, Paris Green [CuAs2O4.Cu(Ac)2] for the color blue, potassium salts such as potassium chloride for the color purple or violet, and magnesium, aluminum, antimony salts such as antimony sulfide (Sb2S3) for the color white. Combinations of these and other metal salts may be used to provide additional colors, such as orange from a combination of calcium carbonate and sodium nitrate, red-purple from a combination of copper sulfide and strontium nitrate, and yellow from a combination of barium nitrate and sodium nitrate. Other metal salts such as cadmium, uranium, gold, mercury, arsenic, iron and lead may be used to provide other colors if desired, although many such salts are not generally preferred due to toxicity. Nitrate salts are generally more preferred than chloride salts as chloride salts tend to occur as hydrates and thus contribute undesired water. The colorant is generally added in amounts from about 0.5 percent by weight to about 20 percent by weight, preferably from about 1 percent by weight to about 10 percent by weight based on the total weight of fuel, oxidant and colorant. These additional salts may include metal salts of calcium, titanium, aluminum, magnesium, and the like. Metal flakes or particles may be added to the pyrotechnic compositions to provide a glitter effect. Suitable metals can include aluminum, magnesium, titanium and iron. Iron can generally be added in the form of steel shavings to avoid rusting problems from moisture.
One preferred pyrotechnic formulation includes a triazolyl-tetrazinyl-aminotriazine compound together with two parts ammonium perchlorate as the oxidizer for complete oxidation, with from about 10 percent by weight of a colorant. It is most preferred that the triazolyl-tetrazinyl-aminotriazine compound comprises a salt of cobalt or copper.
The pyrotechnic composition is formed from mixing or packing the triazolyl-tetrazinyl-aminotriazine compound, including its salt or complex, in an appropriate delivery combination for use as fireworks, with the appropriate mixing and packing being within the capabilities of a person of ordinary skill in the art of manufacturing fireworks. The triazolyl-tetrazinyl-aminotriazine compound is diazotized from the triazolyl-triaminotriazine precursor, as taught herein, to form the appropriate pyrotechnic salt. Diazotization occurs by reacting the triazolyl-triaminotriazine precursor with a nitrite salt, such as, without limitation, nitric oxide, sodium nitrite, potassium nitrite and the like. The triazolyl-triaminotriazine precursor(s), including the acid salts thereof, are diazotized in an appropriate aqueous acid, such as for example hydrochloric or sulfuric acid, with the nitrite salt to give the ring-closed tetrazine product of the triazolyl-tetrazinyl-aminotriazine compound. The use of sodium nitrite (Zxe2x95x90Na) to form the triazolyl-tetrazinyl-aminotriazine compound is preferred. The triazolyl-tetrazinyl-aminotriazine compound (Zxe2x95x90Na) can be acidified to produce the parent acid of the triazolyl-tetrazinyl-aminotriazine compound (i.e., Zxe2x95x90H). Other triazolyl-tetrazinyl-aminotriazine compounds may be formed by neutralization of the parent acid or by cation exchange reactions with the sodium salt. 
The preparation of triazolyl-tetrazinyl-aminotriazine salts by neutralization of the parent acid (Method A) occurs by reaction with amine bases or by reaction with metal hydroxides. Cation exchange with the sodium salt to form the triazolyl-tetrazinyl-aminotriazine salts (Method B) occurs by the process that includes an aqueous solution of the sodium salt being mixed with a solution of barium nitrate, strontium nitrate, calcium nitrate, or other.
The precursor comprises a 1,2,4-triazolo[4,3-a][1,3,5]triazine-3,5,7-triamine, acid salt or its neutralized form of 1,2,4-triazolo[4,3-a][1,3,5]triazine-3,5,7-triamine. The general process involves ring closure of 2,4-diamino-6-hydrazino-s-triazine with an acid and a chemical of the general formula RCN where the R comprises a leaving group, and then neutralizing the acid. 
The structure of the precursor is shown below: 
More specifically, the 1,2,4-triazolo[4,3-a][1,3,5]triazine-3,5,7-triamine, acid salt is derived first by obtaining or synthesizing 2,4-diamino-6-hydrazino-s-triazine. One method for synthesizing this chemical is set forth in U.S. Pat. No. 3,061,605 by D""Alelio. The general method is to effect a reaction between 2,4-diamino-6-chloro-1,3,5-triazine and hydrazine. A specific example is set forth in column 3, lines 60-70 of the above patent which is hereby incorporated by reference. While this particular method of synthesizing 2,4-diamino-6-hydrazino-s-triazine is specifically disclosed, any prior art method of synthesis would be appropriate to practice the present invention. The 2,4-diamino-6-hydrazino-s-triazine is dissolved with an acid, preferably out at room temperature with an acid that is of sufficient strength to dissolve the 2,4-diamino-6-hydrazino-s-triazine. Many acids can be employed in the present invention, such as sulfuric acid or hydrochloric acid or mixtures of these acids with other solvents such as methanol or ethanol, and may be selected by one skilled in the art. One preferred acid is 1N hydrochloric acid. The dissolved 2,4-diamino-6-hydrazino-s-triazine is mixed with a reagent of the formula RCN, wherein R comprises a leaving group. This reaction will provide the amino triazole ring on the product directly. A leaving group, as used in this application, is a group that can be displaced to give ring closure; that is, produces the amino triazole ring. One preferred leaving group comprises bromine wherein the reagent comprises cyanogen bromide. Although the reaction in this step is acid catalyzed, preferred reaction times range from about twenty hours to about thirty hours in order to allow for the maximum formation of acid salt crystals. It is also preferred that the acid salt crystals be removed after the reaction is substantially complete, approximately thirty hours, to prohibit contamination of the final product with impurities. The crystals may be removed by any normal method, such as filtration, and can then be washed and dried in order to obtain the final acid salt product.
Neutralization of the 1,2,4-triazolo[4,3-a][1,3,5]triazine-3,5,7-triamine, acid salt crystals synthesized above to obtain a final product of 1,2,4-triazolo[4,3-a][1,3,5]triazine-3,5,7-triamine is accomplished by mixing the crystals with a substance more basic than 1,2,4-triazolo[4,3-a][1,3,5]triazine-3,5,7-triamine. This step results in the removal of the acid from the above reaction and provides for a final product of 1,2,4-triazolo[4,3-a][1,3,5]triazine-3,5,7-triamine. The substance used in this final step may be selected by one skilled in the art based upon the basicity of the substance versus the basicity of 1,2,4-triazolo[4,3-a][1,3,5]triazine-3,5,7-triamine. Some examples are potassium carbonate, potassium acetate, sodium bicarbonate, and sodium hydroxide. One preferred substance is potassium carbonate. It is also preferred that the reaction take place in solution, so preferably, water or some other solvent may be added to the salt.
The following examples (Examples 1A-1C) are preparations of the 1,2,4-triazolo[4,3-a][1,3,5]triazine-3,5,7-triamine precursors: